Paul,

   Tracy built a mount with no offset (as did I based on Tracy's

input).

 Which is not the same as what your talking about. The stock mount

for my RV

 has offset going the wrong way for the Mazda/RD1 combo. I cant

imagine that

 this wouldnt be noticeable so have to believe that the new front

housing

 would at the least need to compensate to get everything back to a

zero

 thrust angle.

 > Mike Wills

This would be no problem at all if Tracy went to the 2.85:1 PSRU.
Prop rotates in right direction.

Paul Lamar

Tailwind engine mounts have no offset in theory.  In fact, most of
them are built in space without a fixture of any kind and you can
imagine that many of them must warped out of alignment, one way or
the other. Difficult to see once the engine is installed.   Yet first
flight reports usually say that the airplane flies normally.   I
personally have flown in three TWs that had motor mounts built
without a fixture and all three felt about the same to me and had no
trim issues.  Also, it is quite possible to kick an engine mount one
way or the other with spacers at the firewall . I saw a Cassutt racer
with 3/4" spacers on one side, none on the other.  Apparently helped
turning left.   The Tailwind does off set the leading edge of the
vert. stab 1/2".  I moved this to the opposite side for the rotary.
Jerry

   After I built the mount for my RV-4  I was curious as to how far off
the thrust line was.  I cut circular spacers out of plastic (with a hole
in the center) to fit the rear rotor housing where the stationary gear
fits and the other fit in place of the front cover oil seal.  I then
marked the firewall with a 'X'  for the thrustline.  Then from about 2
feet away I just sighted thru the holes like a rifle 'peek' site.  I
couldn't believe it but the engine is dead on the 'X'.  I will admit
that this was mostly luck on my part.  I built everything in a jig but I
know that it is REALLY hard for an ameteur to get things straight.  I
couldn't do it again in a hundred years!!!!  But I have pictures to
prove it.
   BTW, I built my engine mount to cantilever off the back of the engine
like a Lyc conical mount.  Many thanks to the engineers on the list for
their help, I could not have made this mount safe without their advice
and help.  The complete mount (both engine adapter, Barry rubber mounts,
and modified Van's RV-4 mount) weighe 19 pounds (I hope I remember that
correctly).  After all the recent posts on engine mounts, I think you
can see why I went to the trouble to get help in designing a mount that
did not place any tubes near the exhaust system.  Actually, Mike Wills
was the person who got me to looking at alternative mounts.  Thanks
Mike, Paul, Monty, Bill and Bill, and the other engineer types for your
help!

Ken Powell

 
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